This study investigates the predictive validity of students' levels of critical thinking disposition, as measured by the California Measure of Mental Motivation (CM3; Giancarlo, Blohm, & Urdan, 2004) for students' math achievement, as measured by the Mathematics assessment included in the Florida Comprehensive Assessment Test (FCAT). The CM3 is a general inventory of critical thinking dispositions. It is not curricula or subject-area specific. Through four independent studies, the authors of the CM3 established it as an appropriate tool for the assessment of secondary students' critical thinking dispositions. The CM3 is a twenty-five item, four category Likert-style student questionnaire comprising four sub-scales (Learning Orientation, Creative Problem Solving, Mental Focus, and Cognitive Integrity). The study site is a north Florida, low-SES (socioeconomic status), high minority suburban middle school (N = 812) with a magnet program for academically advanced students that serves approximately one-third of the student body. Preliminary results indicate small to moderate statistically significant correlations between students' math achievement and critical thinking disposition for three of the four subscales on the CM3. (Contains 1 table.)